1. Field of the Invention
The present invention generally relates to a fingerprint sensing method, and more particularly, relates to a thermal imaging method of fingerprint using thermoelectric sensor and its IC compatible fabrication The present invention is partially related to U.S. Pat. No. 6,300,554 B1 entitled “METHOD OF FABRICATING THERMOELECTRIC SENSOR AND THERMOELECTRIC SENSOR DEVICE” and U.S. Pat. No. 6,335,478 B1 entitled “THERMOPILE INFRARED SENSOR, THERMOPILE INFRARED SENSOR ARRAY, AND METHOD OF MANUFACTURING THE SAME”.
2. Description of the Prior Art
Early methods of fingerprinting utilized ink to transfer the fingerprint onto paper for checking directly or optically scanning the fingerprint into a computer to compare with a stored database for personal verification or authentication. The major problem with these methods is that they cannot provide a real-time solution to satisfy the increasing demands of such applications as internet security, electronic transactions, handheld electronic device security, personal ID, etc.
For this reason, some real-time fingerprint sensing methods were introduced in the past including optical-types as disclosed in U.S. Pat. Nos. 4,053,228 and 4,340,300; chip-type fingerprint sensors including pressure induced piezoelectric effect or electrically contacting as described in U.S. Pat. Nos. 4,394,773, 5,503,029, 5,400,662, and 5,844,287; capacitance sensing as in U.S. Pat. No. 6,049,620; and finally temperature sensing as in U.S. Pat. No. 6,061,464.
Because of the size of the optics module, the optical type is not suitable for handheld electronic products, such as notebook computers or cellular phones.
The major advantage of the chip-type fingerprint sensor is its small size so that can potentially be embedded into any electronics system. However, the chip-type fingerprint sensor of the prior art has some drawbacks including high power consumption (electrically contacting and temperature sensing ones), non-IC process compatible (piezoelectric and temperature sensing ones), dry or wet finger interference (capacitance), and ESD damage (capacitance).
For these reasons, the present invention provides a chip-type fingerprint sensor with low power consumption, IC process compatible, minor wet or dry finger interference and ESD damage resistance.